var arr=[];
var o={}
var a="hello";
console.log(Array.isArray(arr));
console.log(Array.isArray(o));
console.log(Array.isArray(a));



var arr=[null,undefined,true,20,"hello",function(){}];

var arr1=new Array();
var arr2=new Array(5);
var arr3=new Array(5,1,null,true);
//console.log(arr1.length);
//console.log(arr2.length);
//console.log(arr3.length);
//arr1.length=10;
arr1[5]="hello";
//console.log(arr1);
//console.log(arr1.length);
console.log(typeof arr3);
console.log(arr3.length);
arr3.length=3;
console.log(arr3);
console.log(arr3.length);


















